This invention relates to broadcasting and multicasting in wireless communication.
The following acronyms are used in this description.
Introduction
Recently, the 3rd Generation Partnership Project 2 (3GPP2) approved a new wireless packet data air interface standard called IS-856, sometimes also referred to as 1xEV-DO (see 3GPP2 3GPP2 C.S0024, CDMA2000 High Rate Packet Data Air Interface Specification, Oct. 27, 2000). IS-856 supports high-speed wireless Internet access at speeds of up to 2.54 Mbit/s using only 1.25 MHz spectrum.
A feature of IS-856 is a high-speed forward link common control channel which operates at bit rates of 38.4 and 76.8 kbit/s. At such bit rates, it is possible to deliver a variety of broadcast or multicast applications and services. These include advertising, news distribution, emergency notification, real-time stock quotes, music and video streaming and others. Broadcasting and multicasting (we sometimes use the term xe2x80x9cmulticastingxe2x80x9d in a way that includes both xe2x80x9cbroadcastingxe2x80x9d and xe2x80x9cmulticastingxe2x80x9d) provide an efficient way of delivering the same content to multiple users by transmitting only one copy. Such efficiency is particularly important in wireless applications because of spectrum scarcity.
In general, in one aspect, the invention features a method that includes, in a radio access network, delivering multicast packets each identified by a multicast network layer address representing a multicast group of access terminals. The multicast packets are delivered in one or more air link frames using a common control channel that is shared among access terminals in a sector. Each airlink frame carries a multicast air link address that identifies the multicast group of terminals.
Implementations of the invention may include one or more of the following features. The common control channel comprises the control channel of IS-856. The multicast air link address comprises a broadcast or multicast Access Terminal Identifier (ATI). The multicast packets are sent to the radio access network from a router through a radio network controller and a radio node to the sector. The router comprises a packet data serving node, and the multicast packets are sent to the radio access network using a multicast network layer tunnel. The network layer tunnel comprises an IP tunnel using the Generic Routing Encapsulation (GRE) protocol. The router uses a stateless simple link layer protocol to frame the network layer multicast packets for transmission to the access terminals. An access terminal is enabled to join or leave a multicast group. An access terminal joins a multicast group by sending a message to a multicast router. The multicast router comprises a Packet Data Serving Node (PDSN) or a Home Agent (HA) through the Radio Network Controller. An access terminal joins a multicast group by registering out-of-band at a web server, and the multicast router obtains the registration information from the web server. The packets are sent to the radio access network using a reliable protocol involving error detection and retransmission.
In general, in another aspect, the invention features a that includes, in a radio network, sending multicast packets from a router through a radio network controller and a radio node to a radio access network, the router using a stateless simple link layer protocol to frame the network layer multicast packets for transmission to access terminals in the sector.
Implementations of the invention may include one or more of the following features. The router comprises a packet data serving node, and the multicast packets are sent to the radio access network using a multicast network layer tunnel. The network layer tunnel comprises an IP tunnel using the Generic Routing Encapsulation (GRE) protocol. The multicast router comprises a Packet Data Serving Node (PDSN) or a Home Agent (HA). The airlink frames are sent repetitively in multiple Control Channel Cycles in order to reach dormant terminals. The radio access network sends a multicast page to multiple terminals in order to wake them up before the transmission of multicast data starts.
Other advantages and features will become apparent from the following description and from the claims.